Description: This function allows the user to extend a line by a specified distance along the axis of the line at either end of the line.
Usage:
1. DSI prompts:
> SELECT LINE TO EXTEND
2. DSI prompts:
> SELECT END POINT TO EXTEND LINE
• Select the desired end point of the line to extend.
3. DSI prompts:
> ENTER LENGTH TO BE EXTENDED
• Input any real number.
4. Selecting UNDO will undo the last extend operation.